US2866125A - Cathode-ray tube - Google Patents

Cathode-ray tube Download PDF

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Publication number
US2866125A
US2866125A US460744A US46074454A US2866125A US 2866125 A US2866125 A US 2866125A US 460744 A US460744 A US 460744A US 46074454 A US46074454 A US 46074454A US 2866125 A US2866125 A US 2866125A
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Prior art keywords
deflection
coil
screen
plane
tube
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Expired - Lifetime
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US460744A
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English (en)
Inventor
Haantjes Johan
Lubben Gerrit Jan
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US Philips Corp
North American Philips Co Inc
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US Philips Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/70—Arrangements for deflecting ray or beam
    • H01J29/72—Arrangements for deflecting ray or beam along one straight line or along two perpendicular straight lines
    • H01J29/76—Deflecting by magnetic fields only

Definitions

  • the distortion-which is not dependent upon the diameter b of the beam such as barrel or pincushion distortion, maybe suppressed by providing, for example, magnets outside the tube.
  • the curvature of the image field may be suppressed by modulating suitable components of pictureand. line fre quency on the concentrating field of .the focusing coil.
  • astigmatism and coma then still remain as errors.
  • the primary object of the inventiomis to provide a cathode ray tube comprising a deflection coil system of the kind above described, in which the astigmatism is considerably reduced.
  • a further. object of the'invention is to obtain a considerably decrezsed'coma.
  • Figs. 1 and 2 serve to explain the occurrence of errors inthe image and the decrease thereof.
  • Fig. 3 shows a cathode-ray tuie comprising a deflection system according to part of one embodirnmt of the invention for deflection in one direction.
  • Fig. 4 shows the associated system for deflection in the second direction.
  • Fig. 5 is a developed view of the coil of Fig. 3 in a flat plane.
  • Fig. 6 is a developed view of the coil of Fig. 4 in a fiat plane.
  • Fig. 7 serves to explain the magnitudes occurring with the coils of Figs. 3 and 4.
  • Fig. 8 is a side-view of another embodiment of the invention.
  • Figs. 9 and 9 are other side views of the same embodiment so far as one direction of deflection is concerned.
  • Figs. 10 and 10 are other side views of the embodiment of Fig. 8 so far as the second direction of deflection is concerned.
  • Fig. 11 shows one embodiment of a circuit arrangement for the parts of the coil shown in Fig. 8 and Fig; 12 shows a second embodiment of such a circuit arrangement.
  • Figt'l shows a rectangular system of axes x, ij, z, the origin 0 of which coincides wiih the deflecim centre, imagined tobe concentrated at one print, of a deflection coil system which is not shown.
  • This coil system serves for the deflection in the x and 1' directions of a beam which in the non-deflected prsition is concentrated around the axis of the tube, in this case the z-axis, and of which the electrons travel in the direction of the positive z-axis.
  • the beam is constituted by three cathode rays provided by three electron guns 1, 2, 3 which are positioned symmetrically about the z-axis.
  • the beam diverges till it reaches the concentrating field, the action of which is imagined to be concentrated in a plane at right angles to the z-axis and passing through point 5.
  • the beam converges after having passed the concentrating field and subsequently traverses the deflection system at 0.
  • the diameter of the beam occurring at 0 determines the magnitude of the errors occurring. If deflection does not take place, the beam converges at point 6 of the z-axis.
  • This image plane 14 is the sagital image plane for deflection in the ij-direction.
  • the circular cross-section 11 is located in the plane of the mean curvature of the image field, of which as before only the intersecting line 15 with the plane x5-b is shown.
  • the plane 15 is a plane having a finite radius of curvature, so that it. does not coincide with the substantially plane screen 7, with the result that a substantially punctiform image does not appear on the screen 7. Consequently, it is commonpractice to control the strength of the concentrating field at as a function of .the deflection in the x and ij-directions.
  • the deflecting field H of the deflection coil system may be described by three relatively perpendicular components H (x, ij, z), H -(x, ij, z) and H (x, i]', z), all three of which may be dependent upon x, ij and 2, as shown.
  • This field must satisfy the following conditions of symmetry:
  • H H and H are coeflicients which are .only dependent uponz.
  • An .accent meansa differentiation 7 with respect to z.
  • the components for the deflection in the x direction are of a similar form, which is found by interchanging x and ii in the righthand terms of the equations.
  • H determines the sign of the direction of deflection.
  • the sign of H always refers to that sign which occurs if H is positive.
  • the electron paths may be calculated with the aid of the Fermat principle that the paths chosen by the electrons between two points are the paths between these points for which the travelling time is a minimum.
  • the deflection I] in the ij-direction is independent of the initial conditions, viz.
  • the subscript s refers to points located at or values determined at the planar screen 7.
  • a first recognition underlying the invention is a choice of the cross-section of the beam such that it is yet possible to obtain a flat plane of convergence as far as astigmatism and coma is concerned.
  • the beam is given a ribbon-like shape.
  • the three electron guns are arranged, for example, on one line,-which 1ine coincides with one direction. of deflection. The three beams together then constitute one ribbon-like beam.
  • [3 :0 implies a deflection proportional to the field strength.
  • a positive value of 3 means that the deflections of the beam at the screen are greater than proportional to the field strength and therefore to the current in the deflection coil. If 13., is negative, the deflection is less than proportional to this current.
  • the meridional image plane thus must be a flat plane for the deflection coil bringing about deflection in a direction parallel to the largest transverse dimension of the ribbon-like beam, whereas the sagital image plane must be a flat plane for the 'deflection'coil bringing about deflection in a direction at right angles to thelargest transverse dimension.
  • the first integral is positive, so that the second integral must be negative, in order that 5 :0.
  • H must be substantially positive through the length of the coil, since' the deflection H is negative with a positive field in the x-direction.
  • the variation of H as a function of z may be fairly arbitrary, provided that the value of the integral does not vary.
  • the largest contribution to the integral is provided by the values of H at high value of z and hence at that end of the coil system which is adjacent the screen, since both I] and (zz increase quadratically with z. Consequently, at the said end of the coil, the mean value of H will have to be positive. This means that in avoiding this distortion, the ij-component of the field strength should increase a certain extent in the direction of deflection.
  • X and U therein arethe first-order deflections in the plane 2:2, in the x and ij-directions.
  • the A-coefl'icients are integral functions of the values H and H (hence H and H of coil [1 deflecting in the X-direction) and the B-coeflicients are integral functions of the values H and H (hence H and 1-1 of coil I deflecting in the ij-direction).
  • the subscripts I refer to values associated with a coil I having a main field component in the x-direction, and the subscripts II with a coil II having amain field component in the ij-direction.
  • the first three integrals together always provide a negative contribution with the conventional dimensions of the cathode-ray tubes and the coeflicients deflection coil systems.
  • the two latter terms containing the H and the H thus have to provide together a positive contribution.
  • With the latter two integrals the values of H at the end of the coil which is adjacent the screen of the coil.
  • the cathode-ray tube .21 in Fig. 3 comprises three electron guns for producing three cathode rays 22, 23,
  • the cathode rays pass on their way to a screen 25 through the field of a concentrating coil 26 of known is constant throughout the length of the coil.
  • the two coil halves 27a and 27b serve for deflection or the cathode rays in a vertical direction, it is necessary to ensure that the three cathode rays '22, 23, 24 upon entering the deflection space are located within a ribbon-like space, of which the largest dimension, as measured at right angles to the axis of the neck 29 of the tube, is also located in a vertical direction.
  • the coil halves 27a and 2712 are formed in a shape such that the value is positive, as measured at the extremity of the coil halves which is adjacent the screen 25 of the tube.
  • the value h constitutes a proper approximation of the quotient for the form of the coils to be discussed.
  • Fig. 7 the importance of the angle p and, of the radius R is shown more fully by a cross-section of an arbitrary deflection coil in a plane at right angles to the axis of a tube.
  • One half of the coil comprises conductors 29a and 291), which are usually constituted by a plurality of relatively insulated wires.
  • the other half of the coil comprises conductors 30a and 30b. It is shown in dotted lines that, on the one hand, the conductors 29a and 2% are interconnected at the front and the rear side of the coil and on the other hand, the conductors 30a and 3%. The figure shows that the coil does not surround the tube completely and that the portion which is not embraced is equal to an angle 4 h.
  • the neck of the tube is circular-cylindrical and if the conductors engage either the neck or a surface concentrical therewith, the distance R between the centre of each conductor and the axis of the neck of the tube This is ever, due to the asymmetric shape, this results in variation of the value of the angle 0, which angle thus has difie'rent values for cross-sections of the coil at different areas.
  • the value It must be negative at the extremity '32 and hence also on the side must be substantially zero for both pairs of coil halves 27a, 27b and 28a, 28b.
  • the coil halves27a and 28a have'the shape as shown in the developed state in Figs. 5 and 6, respectively.
  • dotted lines indicate the location :of the conductors of the coil halves which are active for the deflection, if it would invariably be zero throughout the length of the coil, which lines thus correspond to an angle 1/ of 30".
  • the coils instead of surrounding a circular-cylindrical portion of the neck of the tube, are located wholly or in part on a conical surface, not only the angle 1/ varies in the longitudinal direction of the coil, but also the radius R varies in the quantity In this case also the said conditions must be fulfilled.
  • a cathode-ray tube comprising a deflection coil system as described above permits of obtaining punctiforrn images of the cathode rays 22, 23, 24 on the screen 25, which images are also substantially free from coma. If the beams 22, 23, 24 occur simultaneously, they provide together only one punctiform image which is likewise substantially free from coma.
  • Fig. 8 shows another embodiment of the deflection coil system. As before, it assumed that the largest transverse dimension of the ribbon-like cathode-ray beam extends in the ii-direction.
  • Two rings 33 and 34 of ferromagnetic material surrounding the neck of the cathode-ray tube are located one after another along the axis of the tube.
  • the rings have toroidally wound on them several coil packages.
  • the deflection coil system for deflection in the x-direction is constituted by a first set of four coil packages wound on ring 33 and by a second set of four coil package wound on ring 34. Since Fig. 8 is a side view from the x-direction, only two packages 35 and 36 of the first set of four packages located on ring 33 can be seen.
  • .coil on ring 34 has a positive H -value.
  • Fig. 9a is a side view of ring 33 from the z-direction.
  • Fig. 9a also shOWs the location of the two other coil packages 37 and 38 of the first set of four.
  • Fig. 8 also shows only the packages 39 and 40.
  • Fig. 9b is a side-view of ring'34 in the z-direction in which the other coil packages 41 and 42 of the second set of four are also seen.
  • Figs. 9a' and 9b also indicate, on the ij-axis, the orientation of the ribbon-like beam produced by the three electron guns 1, 2 and 3.
  • the coil packages are interconnected in a manner which will be described hereinafter. Consequently, the packages 35,
  • the current thus flows in opposite directions through two diametrically opposing packages 36, 37 or 35, 38
  • H -values may be varied by variation of the corresponding angles.
  • H -value may be controlled by suitable choice of the numbers of ampereturns on ring 33 and ring 34 for each coil system. It is thus also possible to ensure that the absolute value of H on the side adjacent the screen, of the coil system for deflection in tie x-direction is higher than the absolute value of H ,'on the side adjacent the screen, of the system for deflection in the ii-direction. Furthermore, it 7 can be ensuredthat the mean H -value throughout the length of the coil is substantially zero for each coil system.
  • the complete deflection coil for deflection in the x-direction thus comprises a part which is remote from the screen, viz. ring 33 together with the packages 35, 36, 37,38, of which H is positive, and a part which is adjacent the screen, viz. ring 34 together with the packages 39, 40, 41, 42, of which H is negative.
  • the coil system for deflection in the z'j-direction is arranged on the same rings 33 and 34.
  • the ring 33 carries the four coil packages 45, 46, 47, 48, of which only two, viz. 4S and 46 are seen in Fig. 8 and are indicated in dotted lines in distinction from the other coil system.
  • Fig. 10a is a side-view in the z-direction of ring 33 and Fig. 101) of ring 34.
  • the ring 34 carries four coil packages 49, 50, 51, 52.
  • the number of ampere-turns of the coil packages 45, 46, 47, 48 and 49, 50, 51, 52 were in a relationship of 8:5 and those of the coil packages 35, 36, 37, 38 and 39, 4h, 41, 42 in a relationship of 5:2.
  • the largest transverse dimension of the ribbon-shaped beam is equal to 20 mms.
  • the diameter of the coils, that is of the central layer of the rings, was 70 mms.
  • the total length of the coil system and hence from point 53 to point 54 in Fig. 8 was 60 mms. and the distance between the centre of the coil system and the screen was 350 mms.
  • Fig. 11 shows a possible manner of feeding the coil packages of the system for deflection in the ij-direction.
  • the coil packages 45, 46, 47, 48 arranged on ring 33 are connected in series, care being taken to connect each part in such manner that the direction of current in each coil package has the correct polarity relative to the direction of the z-axis.
  • Each series-connection furthermore includes one half of a coil 55 having a slidable core 56.
  • the resultant seriesconnections are connected in parallel between supply terminals 57 and S8, to which a sawtooth current is supplied.
  • the distribution of current through the two parallel branches may be varied by sliding the core 56, so that the numbers of ampere-turns for the system on ring 33 and for the system on ring 34 are relatively varied.
  • the coil 55 is arranged in such manner that the deflection of the beam is not influenced by it.
  • the coil packages 45, 46, 47, 43 are included in one branch of a bridge circuit and the coil packages 49, 50, 51, 52 are included in a second branch thereof.
  • the third branch is constituted by one half of a coil 59 and the fourth branch by the other half of coil 59, which, as before, comprises an adjustable core 60.
  • a diagonal 63 of the bridge is connected between the centre of core 59 and the junction of the two sets of four coil'packages. The other diagonal has connected to it input terminals 61 and 62 for supply of the sawtooth current. If the bridge circuit is in equilibrium, which may be ensured by adjustment of the core 60, the diagonal 63 is currentless and the same cated in Figs. 10a and 1017, now corresponds to 33 in Y Fig. 100: and to 20 in Fig. 10b.
  • the part of the deflection coil on ring 33 thus exhibits a H -value which is negative and the part of the
  • the deflection system for the deflection parallel to the ribbon-shaped beam that is to say the ii-direction (coil system shown in Figs. 10.1 and 10b) has apredorninantly positivefi current flows through the two sets of four coil packages.
  • the coil 59 is arranged in such manner that the deflection of the beam is not influenced by it.
  • a cathode-ray tube having a substantially planar electron-receiving screen extending substantially at right angles to the longitudinal axis of the tube and means including a plurality of electron guns for producing a common electron beam having a substantially ribbon-like shape along the axis of said tube;
  • a cathode r'ay tube having at one end a substantially planar electron-receiving screen extending'sub stantially at right angles to the longitudinal axis of the tube and at the other end a plurality of electron guns each producing a stream of electrons directed at said screen, said electron guns being located adjacent one another and extending substantially in a common plane, thereby jointly producing an electron beam having a substantially ribbon-like shape along the axis of said tube; means intermediate said guns and screen for producing a field for focussing said beam onto said screen; and electromagnetic deflection means located between said electron guns and said screen for producing a deflecting field within thetube for deflecting said electron beam in two substantially perpendicular directions, whereby said beam may be caused to scan said screen, said ribbon-shaped beam having a longer and a shorter dimension both at right angles to one another and to the axis of the tube, said longer dimension of said beam extending parallel to one direction of deflection of the beam at said deflection means, said deflection
  • a cathode-ray tube having a substantially planar electron-receiving screen extending substantially at right angles to the longitudinal axis of the tube and a plurality of electron guns each producing a stream of electrons directed at said screen, said electron guns being located adjacent one another and extending substantially in a common plane, thereby jointly producing an electron beam having a substantially ribbon-like shape along the axis of said tube; and electromagnetic deflection means located between said electron guns and said screen for producing a deflecting field within the tube for deflecting said electron beam in two substantially perpendicular directions, whereby said beam may scan said screen, said ribbon-shaped beam having a longer and a shorter dimension both at right angles to one another and to the axis of the tube, said longer dimension of said beam extending parallel to one direction of deflection of the beam, wherein said tube axis corresponds to the z axis of a rectangular system of coordinates, said one direction of deflection corresponds to the ij axis and said other direction of deflection
  • a cathode-ray tube having a substantially planar electron-receiving screen extending substantially at right angels to the longitudinal axis of the tube and means including a plurality of electron guns for producing a combined electron beam having a substantially ribbon-like shape along the axis of said tube; and electromagnetic deflection means located between said electron guns and said screen for producing a deflecting field within the tube for deflecting said electron beam in two substantially perpendicular directions, whereby said beam may be caused to scan said screen, said ribbon-like beam having a longer and a shorter dimension both at right angles to one another and to the axis of the tube, said longer dimension of said beam extending parallel to one direction of deflection of the beam at said deflection means; said deflection means including first and second ferromagnetic annular members surrounding the tube with the second member being closer to the screen than the first member, a first coil system for deflecting said beam in said one direction of deflection comprising a first set of four coils wound toroidally on the
  • each set of four coils being mounted substantially diametrically opposite one another and being connected so as to be traversed by deflection currentin opposite senses, whereby said deflection means produce a deflection field 'in which the meridional image plane for said 7 one direction is substantially coincident with the surface of said screen, and the sagi-tal image plane for the other direction of deflection is also substantially coincident with the surface of said screen.
  • a cathode-ray tube having a sub stantially planar electron-receiving screen extending-substantially at right angles to the longitudinal axis of the tube and means including a plurality of electron guns for producing an electron beam having a substantially ribbonlike shape along the axis of said tube; and electromagnetic deflection means located between said electron guns and said screen for producing a deflecting field within the tube for deflecting said electron beam in two substantially perpendicular directions, whereby said beam may be caused to scan said screen, said ribbon-like beam having a longer and a shorter dimension both at right angles to one another and to the axis of the'tube, said longer dimension of said beam extending parallel to one direction of deflection of the beam at said deflection means; said deflection means including a first pair of coil halves diametrically surrounding the tube for deflection in said one direction and a second pair of coil halves diametrically surrounding the tube between and symmetrically relative to the first pair for deflection in the other direction,
  • R R is the radius from the tube axis to the coil halves, and 11/ is equal to one-quarter of the angle of the tube not embraced by the coil halves, said two pairs of coil halves producing a field wherein the integral first pair having its wide end adjacent the screen and with the second pair having its narrow end adjacent the screen,
  • Attesfi T. B. MORROW, ROBERT C. WATSON, Atteszxing Ofliaer. Commissioner of Patents.

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US460744A 1954-02-09 1954-10-06 Cathode-ray tube Expired - Lifetime US2866125A (en)

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NL335427X 1954-02-09
NL280654X 1954-06-28

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US (1) US2866125A (es)
BE (1) BE535542A (es)
CH (1) CH335427A (es)
DE (1) DE1107835B (es)
FR (1) FR1122284A (es)
GB (1) GB790427A (es)
NL (1) NL110569C (es)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3195025A (en) * 1956-04-25 1965-07-13 Hazeltine Research Inc Magnetic deflection yoke
US3524094A (en) * 1967-12-22 1970-08-11 Philips Corp Wide deflection angle cathode-ray tube with a lens for focussing the electron-beam at an elongate spot on a screen and an astigmatic correcting lens
US3714500A (en) * 1969-06-27 1973-01-30 Philips Corp Color television display device
US3733507A (en) * 1968-09-16 1973-05-15 France Couleur Soc Beam-deflection system for color television picture tube
US3851215A (en) * 1971-09-21 1974-11-26 Philips Corp Deflection coil system for colour television
US3857057A (en) * 1971-12-22 1974-12-24 Philips Corp Colour television display apparatus provided with a picture display tube with electron beams generated in one plane
DE2544294A1 (de) * 1974-10-04 1976-04-08 Rca Corp Farbbild-sichtgeraet
US3970890A (en) * 1974-01-23 1976-07-20 U.S. Philips Corporation Plural beam cathode ray tube including an astigmatic electron lens and self-converging
EP0059004A1 (en) * 1981-02-18 1982-09-01 Koninklijke Philips Electronics N.V. Picture display tube and display device provided with such a tube
EP0456224A2 (en) * 1990-05-10 1991-11-13 Kabushiki Kaisha Toshiba Color cathode ray tube apparatus

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3800176A (en) * 1972-01-14 1974-03-26 Rca Corp Self-converging color image display system
JPS5337322A (en) * 1976-04-09 1978-04-06 Hitachi Ltd Deflection york

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2165028A (en) * 1933-12-29 1939-07-04 Emi Ltd Television and the like system employing cathode ray tubes
US2170944A (en) * 1937-05-29 1939-08-29 Bell Telephone Labor Inc Multicathode ray discharge device
US2172733A (en) * 1935-03-29 1939-09-12 Deflection coil
US2455171A (en) * 1943-09-08 1948-11-30 Hartford Nat Bank & Trust Co System for magnetic deflection in cathode-ray tubes
US2595548A (en) * 1947-02-24 1952-05-06 Rca Corp Picture reproducing apparatus
US2617059A (en) * 1949-12-02 1952-11-04 Hartford Nat Bank & Trust Co Cathode-ray tube

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE879729C (de) * 1938-01-26 1953-06-15 Hermann Dr Phil Habil Hinderer Kathodenstrahloszillograph fuer Mehrfachaufnahmen
US2457175A (en) * 1946-12-19 1948-12-28 Fed Telecomm Lab Inc Projection cathode-ray tube

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2165028A (en) * 1933-12-29 1939-07-04 Emi Ltd Television and the like system employing cathode ray tubes
US2172733A (en) * 1935-03-29 1939-09-12 Deflection coil
US2170944A (en) * 1937-05-29 1939-08-29 Bell Telephone Labor Inc Multicathode ray discharge device
US2455171A (en) * 1943-09-08 1948-11-30 Hartford Nat Bank & Trust Co System for magnetic deflection in cathode-ray tubes
US2595548A (en) * 1947-02-24 1952-05-06 Rca Corp Picture reproducing apparatus
US2617059A (en) * 1949-12-02 1952-11-04 Hartford Nat Bank & Trust Co Cathode-ray tube

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3195025A (en) * 1956-04-25 1965-07-13 Hazeltine Research Inc Magnetic deflection yoke
US3524094A (en) * 1967-12-22 1970-08-11 Philips Corp Wide deflection angle cathode-ray tube with a lens for focussing the electron-beam at an elongate spot on a screen and an astigmatic correcting lens
US3733507A (en) * 1968-09-16 1973-05-15 France Couleur Soc Beam-deflection system for color television picture tube
US3714500A (en) * 1969-06-27 1973-01-30 Philips Corp Color television display device
US3851215A (en) * 1971-09-21 1974-11-26 Philips Corp Deflection coil system for colour television
US3857057A (en) * 1971-12-22 1974-12-24 Philips Corp Colour television display apparatus provided with a picture display tube with electron beams generated in one plane
US3970890A (en) * 1974-01-23 1976-07-20 U.S. Philips Corporation Plural beam cathode ray tube including an astigmatic electron lens and self-converging
DE2544294A1 (de) * 1974-10-04 1976-04-08 Rca Corp Farbbild-sichtgeraet
EP0059004A1 (en) * 1981-02-18 1982-09-01 Koninklijke Philips Electronics N.V. Picture display tube and display device provided with such a tube
EP0456224A2 (en) * 1990-05-10 1991-11-13 Kabushiki Kaisha Toshiba Color cathode ray tube apparatus
EP0456224A3 (en) * 1990-05-10 1993-02-24 Kabushiki Kaisha Toshiba Color cathode ray tube apparatus

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NL110569C (es)
DE1107835B (de) 1961-05-31
BE535542A (es)
GB790427A (en) 1958-02-12
FR1122284A (fr) 1956-09-04
CH335427A (de) 1958-12-31

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